1. Field of the Invention
The present invention relates generally to an electrical coaxial connector, and more particularly to an improvement in an electrical coaxial connector to be mounted on a circuit board for transmitting signals from the circuit board to the outside thereof or to the circuit board from the outside thereof under a condition of electro-magnetic shield.
2. Description of the Prior Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
A high-frequency signal flowing through conductors arranged on a circuit board is mostly dealt with as a signal which requires to be put in a condition of electro-magnetic shield so as to be inactive to leak out from the conductors or to prevent noises from mixing into the signal from the outside when the high-frequency signal is transmitted from the circuit board to the outside thereof or to the circuit board from the outside thereof. For transmitting the high-frequency signal from a specific circuit board to the outside thereof, for example, to another circuit board, or to the specific circuit board from the outside thereof, for example, from another circuit board, under the condition of electro-magnetic shield, an electrical coaxial connector provided to be mounted on the specific circuit board is used.
The electrical coaxial connector thus provided to be mounted on a circuit board comprises usually an insulating base, a signal-joining contacting conductor provided on the insulating base for transferring a signal and a grounding contacting conductor provided on the insulating base for surrounding the signal-joining contacting conductor to be supplied with a ground potential so as to put the signal supplied to the signal-joining contacting conductor in a condition of electro-magnetic shield. In the electrical coaxial connector mounted on the circuit board, the signal-joining contacting conductor is connected with a signal terminal provided on the circuit board and the grounding contacting conductor is connected with a ground-potential terminal provided on the circuit board. When the electrical coaxial connector mounted on the circuit board is put to practical use, the electrical coaxial connector is coupled with a mating coaxial connector which is, for example, another electrical coaxial connector mounted on another circuit board, so that the signal-joining contacting conductor comes into contact with a signal-joining conductor provided in the mating coaxial connector and the grounding contacting conductor comes into contact with a grounding conductor provided in the mating coaxial connector. With the electrical coaxial connector and the mating coaxial connector coupled with each other in such a manner, the signal supplied to the signal-joining contacting conductor in the electrical coaxial connector or to the signal-joining conductor in the mating coaxial connector is transferred to the signal-joining conductor in the mating coaxial connector or to signal-joining contacting conductor in the electrical coaxial connector under the condition of electro-magnetic shield brought about by the grounding contacting conductor in the electrical coaxial connector and the grounding conductor in the mating coaxial connector. Thereby, the signal is transmitted between the circuit boards, on which the electrical coaxial connector and the mating coaxial connector are mounted respectively, under the condition of electro-magnetic shield.
Such an electrical coaxial connector as mentioned above is usually required to be miniaturized to have a reduced measure of thickness in a direction perpendicular to a parts-mountable surface of the circuit board under a condition wherein an electronic apparatus or the like having the circuit board built-in is put in miniaturization and weight saving, and in addition, is desired to reduce assembling time and labor with improved accuracy in assembly so that manufacturing cost is reduced. Further, under a situation wherein the above requirement and desire are filled, when the electrical coaxial connector is coupled with the mating coaxial connector, a condition wherein the signal-joining contacting conductor connected with the signal terminal provided on the circuit board and the ground-connecting contacting conductor connected with the ground-potential terminal provided on the circuit board are properly and surely connected respectively with the signal-joining conductor in the mating coaxial connector and the grounding conductor in the mating coaxial connector, is desired to be stably maintained for a relatively long period of time.
There has been proposed to provide an improved electrical coaxial connector which comprises an isolating base, a signal-joining contacting conductor provided on the insulating base and a grounding contacting conductor provided on the insulating base to surround the signal-joining contacting conductor to be mounted on a circuit board and with which a certain degree of miniaturization to have a reduced measure of thickness of the electrical coaxial connector on the circuit board is realized and it is intended to reduce assembling time and labor and to improve accuracy in assembly so that manufacturing cost is reduced, as disclosed in, for example, the Japanese patent application published before examination under publication number 2009-104836.
The previously proposed electrical coaxial connector (a plug connector (21)) disclosed in the publication mentioned above comprises a signal-joining contacting conductor (a socket type central conductor (22)) provided to be electrically connected with a signal-joining conductor (a pin type central conductor (12)) of a mating coaxial connector (a receptacle connector (11)), an insulating base (a second insulating housing (24)) mounted on a circuit board (a second board (2)) for supporting at its central portion the signal-joining contacting conductor, and a grounding contacting conductor (a second cylindrical outer conductor (23)) formed into a cylindrical shape for surrounding the insulating base supporting the signal-joining contacting conductor on the circuit board. The signal-joining contacting conductor has a top end portion made of a metallic tube and the signal-joining conductor in the mating coaxial connector is inserted into the top end portion of the signal-joining contacting conductor when the signal-joining contacting conductor is connected with the signal-joining conductor in the mating coaxial connector.
In the previously proposed electrical coaxial connector disclosed in the publication mentioned above, any structure impeding miniaturization to have a reduced measure of thickness of the electrical coaxial connector on the circuit board is not perceived. The manufacturing process of the previously proposed electrical coaxial connector includes a first step of producing by means of insert molding the insulating base supporting the signal-joining contacting conductor to be incorporated therewith and a second step of causing the insulating base and the signal-joining contacting conductor incorporated with the insulating base to engage with the inside of the grounding contacting conductor formed into the cylindrical shape so as to be attached thereto. That is, when the previously proposed electrical coaxial connector disclosed in the publication mentioned above, in which the signal-joining contacting conductor and the grounding contacting conductor surrounding the signal-joining contacting conductor are supported by the insulating base, is manufactured, first, the insulating base is produced for supporting the signal-joining contacting conductor to be incorporated with the insulating base by means of the insert molding, and then, the insulating base and the signal-joining contacting conductor incorporated with the insulating base is attached to the inside of the grounding contacting conductor formed into the cylindrical shape.
In such a case, since the signal-joining contacting conductor is incorporated with the insulating base by means of the insert molding in order to obtain the insulating base caused to support the signal-joining contacting conductor, it is expected in production of the insulating base caused to support the signal-joining contacting conductor that assembling time and labor are reduced and accuracy in assembly is improved so that production cost of the insulating base caused to support the signal-joining contacting conductor is reduced. However, since the insulating base and the signal-joining contacting conductor incorporated with the insulating base are attached to the inside of the grounding contacting conductor formed into the cylindrical shape in order to obtain the insulating base caused to support the grounding contacting conductor, it cannot be expected in production of the insulating base caused to support the grounding contacting conductor that assembling time and labor are reduced and accuracy in assembly is improved so that production cost of the insulating base caused to support the grounding contacting conductor is reduced.
In the previously proposed electrical coaxial connector as described above, which is manufactured through the manufacturing process wherein first the signal-joining contacting conductor is incorporated with the insulating base by means of the insert molding and then the insulating base and the signal-joining contacting conductor incorporated with the insulating base are attached to the inside of the grounding contacting conductor formed into the cylindrical shape, since the signal-joining contacting conductor is incorporated with the insulating base by means of the insert molding, the signal-joining contacting conductor is not provided thereon with any projection forming a contact point for coming into contact with the signal-joining conductor in the mating coaxial connector and the signal-joining conductor in the mating coaxial connector is inserted into the top end portion made of the metallic tube of the signal-joining contacting conductor when the signal-joining contacting conductor is connected with the signal-joining conductor in the mating coaxial connector.
With the previously proposed electrical coaxial connector in which the signal-joining contacting conductor without the projection forming the contact point is employed to be connected with the signal-joining conductor in the mating coaxial connector, it is feared that a condition wherein the signal-joining contacting conductor is properly connected with the signal-joining conductor in the mating coaxial connector is not able to be stably maintained when the previously proposed electrical coaxial connector is coupled with the mating coaxial connector.
The reason why the signal-joining contacting conductor of the previously proposed electrical coaxial connector is not provided thereon with any projection forming the contact point for coming into contact with the signal-joining conductor in the mating coaxial connector is that, if a projection forming the contact point is provided on the signal-joining contacting conductor, the insulating base with which the signal-joining contacting conductor has been incorporated by means of the insert molding is obstructed to be removed from a mold used for the insert molding by the projection on the signal-joining contacting conductor and therefore it comes to be quite difficult to cause the signal-joining contacting conductor to be incorporated with the insulating base by means of the insert molding or the mold to be used for the insert molding comes to be quite complicated in its shape and structure.
Further, with the previously proposed electrical coaxial connector as disclosed above, since the insulating base caused to support the grounding contacting conductor is obtained by means of attaching the insulating base and the signal-joining contacting conductor incorporated with the insulating base to the inside of the grounding contacting conductor formed into the cylindrical shape, the assembling time and labor are not reduced and the accuracy in assembly is not improved in the production of the insulating base caused to support the grounding contacting conductor so that the production cost of the insulating base caused to support the grounding contacting conductor is not reduced. Accordingly, as for the previously proposed electrical coaxial connector on the whole, assembling time and labor are not reduced and accuracy in assembly is not improved in manufacturing of the electrical coaxial connector so that manufacturing cost of the electrical coaxial connector is not reduced.